Poles are due to elect a new president on 20 June following the death of Lech Kaczyński, along with 95 other people - mostly senior Polish officials - in a plane crash in Russia on 10 April (EurActiv 10/04/10).
Despite the increase in sympathy for the Kaczyński family, opinion polls show acting President Bronisław Komorowski of the centrist Civic Platform as the most likely election winner.
A snap opinion poll conducted by the Homo Homini agency after Kaczyński's announcement on Monday showed him winning 32% against 46% for Komorowski. Such an outcome would force a second, decisive round of the election on 4 July.
Lech Kaczyński, elected president in 2005, had been expected to lose the election to Komorowski.
"In reality, it won't be him [Jarosław Kaczyński] running, it will be his brother. His campaign team will play on sympathy for his brother," said Krzysztof Bobinski, head of the Unia & Polska Foundation, a Warsaw think-tank.
"Kaczyński would have a chance to win only if other candidates make mistakes. This is a difficult situation for everybody. This is not a normal election campaign but I think political attitudes generally have not changed among voters."
Jarosław Kaczyński, a former prime minister who also heads Poland's main opposition party, the right-wing, eurosceptic Law and Justice (PiS), said he wanted to continue his brother's conservative mission.
"Poland is our great shared obligation. We are required to overcome our personal pain and to take on this mission despite the personal tragedy. That's why I have taken the decision to run for the presidency of Poland," he said in a statement.
Lech Kaczyński and his wife, Maria, were buried in a state funeral in Krakow on 18 April (see EurActiv Poland 19/04/10). Komorowski took over as acting president in his capacity as speaker of parliament, the second highest ranking position in Poland's state hierarchy.
Sympathy vote
The decision to run will have been difficult for Kaczyński both personally and politically. Many Poles regard him as a divisive figure whose spell as premier in 2006-7 put a strain on Poland's relations with Germany, Russia and the EU.
Polish media also say he has yet to tell his ailing 83-year-old mother of Lech's death.
The election outcome matters for Poland, the European Union's largest ex-communist member. Although Prime Minister Donald Tusk and his government hold most power, the president can veto laws and also has a say in foreign and security policy.
Lech Kaczyński had irked the Tusk government by blocking health, pension and media reforms. He and Jaroslaw had also resisted government efforts to push for the swift introduction of the euro in Poland.
The Kaczyński twins were senior members of the pro-democracy Solidarity trade union that toppled communism in 1989. The union no longer has significant political clout but on Monday its leader, Janusz Sniadek, publicly backed Jarosław Kaczyński's presidential bid.
Other candidates for the presidential race include Waldemar Pawlak, whose Peasants' Party is the junior partner in Tusk's coalition, and Grzegorz Napieralski, leader of the leftist SLD opposition party. Neither is seen winning many votes.
"After the recent events, Polish politics is a lot less predictable," said Rafal Chwedoruk of Warsaw University's Institute of Political Science.
(EurActiv with Reuters.)
